    ::read-note-prefix "bassclefimages"})
 
 (def notes-grand-staff
-  {::read-note-order  ["G" "A" "B" "C" "D" "E" "F" "G" "A" "B" #_"TREMBLE" "D" "E" "F" "G" "A" "B" "C" "D" "E" "F" "C"]
+  {::read-note-order  ["G" "A" "B" "C" "D" "E" "F" "G" "A" "B" #_"TREBLE" "D" "E" "F" "G" "A" "B" "C" "D" "E" "F" "C"]
    ::read-note-prefix "grandstaffimages"})
+
+(defn rand-int-new [n old]
+  "Generate a new random number like rand-int, if number is equals to `old` a new
+  number will be generated until it's different."
+  (loop []
+    (let [x (rand-int n)]
+      (if (= x old)
+        (recur)
+        x))))
 
 (om/defui ^:once ReadingMusic
   static uc/InitialAppState

(defmethod slug->exercise "treble-clef-reading" [name]
  {::name  name
   ::class ReadingMusic
   ::props notes-tremble})

(defmethod slug->exercise "bass-clef-reading" [name]
  {::name  name

    (exercise (om/props this)
      (dom/p #js {:key "p"} "You will hear two notes. Are they an octave apart?"))))

(def notes-treble
  {::read-note-order  ["E" "F" "G" "A" "B" "C" "D" "E" "F"]
   ::read-note-prefix "trebleclefimages"})

